... Specification:Video Input 4 channel composite video, PAL or NTSC BNC interface,1.0Vp-p,impedance 75OhmsVideo Compression H. ... ; BNC, level: 1.0Vp-p, impedance: 75Ω,Audio Compression G.726, G711, ADPCMAudio Input1 channel, RCA port, liner input, ... Impedance:1KOhmsAudio Output1channel,RCA port, linear outputAudio talk-back input1 channel ,MIC portOverlaid CaptionChannel Name, Date, Bit rate, position ...